According to an interview with the Etihad Regional CEO, Etihad Regional has shelved its plans to serve DUS from CBG and LCY due to a lack of suitable slots at the DUS end and will instead take over AB's DUS-STN route with up to four daily flights, using its Saab 2000s and thus freeing up the Q400 currently used by AB to STN.
Not sure if that is a smart move...